In recent times, an increasing demand for efficient and timely remote mobile access to email and the internet, has aroused the need for versatile portable wireless communication devices, especially broadband devices. Mobile communication devices that are designed to operate in many locations around the world have also become increasingly popular.
For such applications, antennas are required to be capable of operating on multiple frequency bands to be compatible with different global standards. In addition, typical portable device antennas are required to be small in size and low in cost.
One approach in realizing an antenna capable of operating on more than one band is to fabricate multiple metalised elements on separate layers of a multilayer dielectric substrate, where each metalised element is designed to resonate at the centre frequency of one of the bands of operation of the antenna. For example, the stacked meander antenna described in European Patent Application EP 1 363 355 comprises two resonating meander elements, one for each band of operation of the antenna. EP 1 363 355 also teaches that, if the antenna is required to operate on three frequency bands, then three meander elements are required.
The provision of separate resonating meander elements for each band of operation of a multi-band antenna is one method to achieve the required electrical characteristics of the multi-band antenna. However, as the number of required bands of operation of the antenna increases, the provision of a separate meander resonator for each band of operation of the antenna increases the overall size and the cost of the multi-band antenna.
It would be desirable, therefore, to provide an antenna capable of operating on N frequency bands, which comprises less than N resonating meander elements.